Which of the following statements is true regarding fuses?

Fuses serve a critical role in electrical circuits by providing protection against overcurrent situations. The statement that they melt to break the circuit during overcurrent accurately reflects their function. When excessive current flows through a fuse, its wire or filament heats up to a point where it melts, effectively interrupting the circuit. This action prevents potential damage to electrical devices and reduces the risk of fire, highlighting the importance of safety in electrical systems.

In contrast, the other statements do not accurately describe the nature of fuses. For instance, fuses cannot be reset or reused once they have melted; they must be replaced after they blow. This is a key difference from circuit breakers, which can be reset. Additionally, fuses are not limited to just low-voltage circuits; they are used in a variety of applications, including high-voltage systems, making their use much broader than suggested in that statement. Thus, the melting action of fuses as a protective measure during an overcurrent is what makes this statement true.